A bandstop filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. More specifically, a band-stop filter is an electronic filter that blocks the frequency component of a signal within a certain range value, where it has its lower cutoff frequency and upper cutoff frequency. However, the frequency component outside that range of value will be passed on.
Bandstop filters usually do not have a wide bandwidth and are constrained by their designed frequencies. As to the latter point, a bandstop filter is limited as to which frequencies can be passed. To accommodate different frequencies, it is necessary to use a different bandstop filters. Accordingly, large chip area needs to be used to accommodate different operating frequencies.